Lotus Elan

Rear brake caliper problems

PostPost by: Spyder fan » Wed Feb 12, 2014 1:56 pm

Been scratching my head on this like yourself and others here. It all appears correct so why is doing that?

Having replaced discs and drive shafts myself I know you need to remove the long bolt holding the hub to the A frame, I see it's loose fitted on your pictures for obvious reasons.

As the A frame has been moved to facilitate getting the shafts and discs off, have you damaged the bushes or distorted the A frame?
Kindest regards

Alan Thomas
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PostPost by: Quart Meg Miles » Wed Feb 12, 2014 3:09 pm

Spyder fan wrote:As the A frame has been moved to facilitate getting the shafts and discs off, have you damaged the bushes or distorted the A frame?

With respect, Alan, the A frame isn't involved, it's all in the hub casting.

Ian, you clearly HAVE assembled it correctly, thanks for the photos, and it looks like Craven suggested that some shims fell out, so if the caliper mating faces are undistorted then fitting a spacer will resolve the problem and restore your sanity. Make it captive then you won't pass the problem on!
Meg

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PostPost by: Spyder fan » Wed Feb 12, 2014 3:32 pm

Ah yes, silly me!

Missing shims is a reasonable theory.
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PostPost by: p.faurie » Wed Feb 12, 2014 4:10 pm

Hi Ian, I be inclined to bolt the new disc to the outer driveshaft as you have already,turn disc to see if there is any run out ,then determine whether it's the disc or the drive shaft ears that are bent, I have never seen any shims anywhere on the calipers, I've had a similar problem when I fitted new discs ,but it turned out to be the driveshaft slightly bent ,good luck

Phil
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PostPost by: Quart Meg Miles » Wed Feb 12, 2014 4:39 pm

p.faurie wrote:Hi Ian, I be inclined to bolt the new disc to the outer driveshaft as you have already,turn disc to see if there is any run out ,then determine whether it's the disc or the drive shaft ears that are bent, I have never seen any shims anywhere on the calipers, I've had a similar problem when I fitted new discs ,but it turned out to be the driveshaft slightly bent ,good luck

Phil

It's certainly worth checking the new discs/ears for runout. I had to make a shim or two (for two new discs) to get within the spec of 0.004". You'll need a dial gauge and stand; try the disc in all three positions and mark the best position clearly on both parts, on the shim position if one is required. Beer cans are good material for such shims but do use an empty one.
Meg

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PostPost by: thorbs000 » Wed Feb 12, 2014 6:19 pm

Hi everybody.

Thanks for all the ideas.
I think looking at it logically, the slightly bent ear looks a good bet.
I can't do anymore before w/e as I have work but I am going to take some measurements from the side that's good and compare with the side that's not and see what I have got. I think measuring from side of disc to the hub and lugs that hold the caliper should tell me if things are out and I will go from there.
Any other ideas gratefully accepted and I will keep you all informed how I go on.
What a great site this really is

Thanks again

Ian
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PostPost by: PacoGago » Sun Jan 10, 2016 2:26 pm

Hi Ian,

As i dropped just in a similar problem as you, did you find already a solution?
I have just installed new discs with new uprated 100 Ton Wheel Shafts and new bearings. Circlips are in their respective positions well alocated in the hubs. One side is OK but the other one has the disc not centered in the calliper (about 1,5 mm deviated) and the disc is interfering with the calliper in a concrete position of the turn.
I will proceed to check first with the roundout of the disc / shaft ears in order to investigate if here resides the problem, and to search the best position for installling the disc in the 3 ears (less amount of runout. Some idea more?

)
Thanks a lot.

Paco.
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PostPost by: mark030358 » Mon Jan 11, 2016 12:44 am

Hi,
Just saw this thread.
If the disc rotates part way then locks up it is one of four things in my opinion...
1) Bent outer drive shaft ears.
2) warped disc.
3) Badly installed outer drive shaft.
4) Caliper mounting on hub bent.

Interested to find out what it was.

Cheers
Mark
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PostPost by: PacoGago » Mon Jan 11, 2016 7:16 am

Hello Mark,

It seemed to be a faulty disc. After checking with a Dial Gauge, i saw that the turning of the disc is not in the same radius, or the center was not well allocated in the manufacturing process. I skimmed at the end a bit ( 1 mm) of a corner in the calliper and now is turning free.
Next time i will take more care at the Quality of the parts.

Thanks.

Paco G.
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PostPost by: patrics » Mon Jan 11, 2016 6:49 pm

Hi Paco,
Would be wise to mark the high spot on the disc, then rotate the disc relative to the hub shaft and mark again and then again for the 3rd locating hole. If it's the disc the high spot will stay in the same location.

Regards
Steve
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PostPost by: vstibbard » Tue Jan 12, 2016 8:06 am

I'd start by measuring the new disks to see that one has not been machined to wrong offset, which is sounds like may be the issue based on the photo's which show it assembled correctly.

I'd see nothing wrong with using a AN hardened washer to shim the caliber if this solved the issue.

As an aside, on my 26R, when fitting TTR rear end we had to make hardened spacers to correctly a;sign the callipers and disks

V
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